Can any diesel car run on biodiesel?

We are thinking of getting a used car with way more seating capacity that we hae now. I’d like something that could run on diesel and/or biodiesel. I’m thinking a used Ford Excursion Diesel might be the right choice for us, but only if it’ll run on biodiesel too.

Would we have to do a conversion of some sort or will it run on biodiesel right out of the box? Will it run on the Diesel that is avaliable now? We live in CA, anything extra to think about there?

I see this car as being stop-gap measure until the new diesels start coming out in the next few years.

Thanks for any advice!

Grist columnist Umbra Fisk is, dare I say it, the Cecil of home-ec environmentalism type questions. She addresses the issue of biodiesel convertibility in this column: